For example, JP 2009-159653 A discloses an illuminating system which includes an illuminating fixture electrically and directly connected to a DC line in a residence or an illuminating fixture electrically connected to a DC line through a wiring device such as a ceiling-mounted socket. Such DC lines each include two DC power supply paths, and are electrically connected to an AC/DC converter provided to a residential power distribution panel. Further, such illuminating fixtures each include a light source powered by a DC voltage to light (emit light) such as a light emitting diode (LED) and an organic electroluminescence element. Since the illuminating fixture lights with DC power supplied through the DC power supply paths, it need not include a power supply circuit such as an AC/DC converter for converting an AC voltage into a DC voltage.
In the illuminating system, the DC power supply paths are used as power supply paths for DC power as well as communication paths (transmission paths). For example, a communication signal (transmission signal) for transmitting data by use of a high frequency carrier is superimposed on a DC voltage. A switch device connected to the DC power supply paths transmits instructions for controlling the illuminating fixture (e.g., turning on, turning off, and dimming) by the transmission signal superimposed on the DC voltage. The illuminating fixture receives the transmission signal transmitted from the switch device and turns on, turns off, or dims a light source according to the control instructions included in the transmission signal.
Note that, in a case where the transmission signal generated by modulating a high frequency carrier is superimposed on a DC voltage like a case of the illuminating system, the indoor wiring is likely to act like an antenna to thus emits electromagnetic waves (considered to be noises), and the transmission signal (considered to be noises) is likely to be leaked to an adjacent residence through a power supply cable. For this reason, in the field of such illuminating systems, it is desired to reduce noises which would be caused by transmission and reception of transmission signals (transmission data).
An object of the present disclosure would be to propose a signal transmitting device, a signal receiving device, a lighting system, an illuminating fixture, and an illuminating system which are capable of reducing noises which would be caused by transmission and reception of transmission data.